Field of the Invention
The present invention relates to a method for putting a primed pluripotent stem cell in a less differentiated state, a method for producing a pluripotent stem cell having an improved chimera forming ability from a primed pluripotent stem cell, and a method for producing a chimeric animal by using the pluripotent stem cell obtained by any of these methods. The present invention also relates to a composition containing a Wnt/β catenin signal inhibitor and a signal transducer and activator of transcription 3 (STAT3) signal activator, a combination of a STAT3 signal activator and a Wnt/β catenin signal inhibitor, and a kit containing the composition or the combination.
Description of the Related Art
A pluripotent stem cell obtained from an inner cell mass (ICM) of a blastocyst is known to have a high chimera forming ability, but a pluripotent stem cell obtained from an embryo at a later developmental stage (such as an embryo after the epiblast stage) is considered to have lost the chimera forming ability (Brons et al., Nature (2007), 448 (7150): 191-195, Tesar et al., Nature (2007), 448 (7150): 196-199, and Han et al., Cell (2010), 143: 617-627).
Pluripotent stem cells are classified into a naive pluripotent stem cell having a high chimera forming ability and a primed pluripotent stem cell having a low chimera forming ability. If a primed pluripotent stem cell can be converted to a naive pluripotent stem cell, the range of selection of cells usable as a cell to be introduced into an embryo in chimera formation can be greatly increased.